The V6 engine also has a pleasing note to it when pressing on, but is virtually silent at freeway speeds, masked by slight rustles of wind noise and tire roar.
But of course, economy and low emissions are the other benefits of the hybrid system.
Fuel economy and emissions
The 2012 Lexus RX 450h AWD is EPA-rated at 30 MPG city, 28 MPG highway and 29 combined.
Our own city route returned a figure of just under 31 MPG--something to be more than happy with. Stop-start traffic allowed the hybrid system to work very effectively.
When driving constantly in EV mode you can expect just over a mile before the engine cuts back in, but some gentler driving around quiet suburban roads allowed us to spend around two thirds of a four-mile journey in EV mode, as the occasional stops and downhill sections kept the battery topped-up.
That's great for saving gas, but there's a good feeling to driving past people's houses without contributing to the local pollution--whether emissions or noise.
The 2013 Lexus RX 450h unveiled at Geneva actually has a dedicated EV mode button, unlike our test car. This could potentially yield even better city figures.
(Note: It's worth pointing out that the even higher MPG figure in our photos is in imperial gallons, rather than U.S. gallons...)
2012 Lexus RX 450h
2012 Lexus RX 450hEnlarge Photo
As we'd been warned, long stretches of freeway were outside the RX's comfort zone. Traveling at between 70-80 mph on continental roads, using the cruise control to set consistent speeds, we struggled to average more than 25 MPG - 3 MPG off the EPA's claims.
Contrary to expectations, there wasn't much advantage to be had dipping down to 65-70 mph. The gently undulating roads never allowed the engine to switch off even on downhill sections. In many ways, traveling at 80 mph was actually beneficial, as downhill sections allowed the engine to back off more and occasionally turn off entirely.
In the interests of fairness we'd point out that using hypermiling techniques, backing off up hills and accelerating down them, and using your right foot rather than the cruise control, yielded slightly better figures.
However, the patience required to do this when driving nine straight hours down France, and the same on the way back, was simply beyond us. We suspect the majority of owners, like us, would make best use of the cruise control over longer distances.
Just as we became disheartened that we were several MPG off the official highway figures, the RX once again redeemed itself. Driving back up the U.K, several hundred miles of awful traffic, stopping and starting, reduced speed limits and more, saw our highway economy leap back up to 30 MPG.
Lexus was right of course--The RX 450h is more suited to city work than freeway driving.
However, if your daily commute takes in traffic-clogged freeways, roadworks and other inconveniences (and unfortunately, many commutes do), then the RX is a relaxing, economical and low-polluting SUV.
There are no doubt more fun and faster SUVs on the market, but few are better for the green-minded luxury car buyer.